GS deserter seeks twin spark help?

[Taipan]

Hi All,

My 03 twin spark Rockster has a problem, which I wrongly thought was TB balance.

The bike seems to have a lot of initial go, but then it sort of fades if you snap the throttle wide open?

At just past 5k there is a definite problem, its almost a misfire. It then tries to clear between 5.5 - 6k , but then dips again? You can really hear the bike struggling at these revs and feel the power delivery jumping about? Best way I can think of describing it is, its like when I put too larger main jet in my KTM. It would run but wouldn't pull high revs properly. if you've re-jetted a carb'ed bike before and run too bigger MJ you may know what I mean by this?

Bike is fitted with a Y piece and Remus (removable baffle in). Apart from that its standard. Removing the baffle doesn't help. Any ideas or has anyone come across this before?

Many thanks.

 

[littleredrooster]

This sounds like the deserter's problem. Should have kept the GS............

Take the hint - the Rockstar doesn't like you.

 

[littleredrooster]

P.S. Try visordown, you deserter.

 

[Taipan]

This sounds like the deserter's problem. Should have kept the GS............

Take the hint - the Rockstar doesn't like you.

Lol, I'm starting to think just that....

 

[pikeydave]

Sounds like a ht coilpack has gone. On the 'main' spark plug you will find not just a plug cap but a whole HT unit (like cars these days) Disconect unit from spark plug. Take a spare spark plug and bung it on the unit and lay it on cylinder head for an earth return and see whether you have any spark/weak spark. Engine will run perfectly happily on the 'aux' plugs. If it is the unit cost is about £45 new.
Hope this helps.

Dave

 

[Straypuss]

Just a though

A lot of Meganes and other cars use these 'pencil' type coils and they fail regularly. GSF sell them. Has anyone looked into compatability/size etc. I don't have access to a twinspark coil to have a look in my ex jobs catalogues.

edit this site has parts fiches for cars and bikes http://www.realoem.com/bmw/

a bike coil is $80 3series car coil $29 !

local mechanics diagnose duff coil by pulling it gently away fron the plug and if you hear it 'clicking as the spark jumps its ok. would have to be done above the rev range that the wee plug works in assuming it is only working at tickover..I'm going on info I read on this site so I could be wrong!

 

[Taipan]

Hi All.

Thanks for the replies.

So if I took the bike to a BMW agent he'd be able to connect up the diagnostics and confirm this right?

Many thanks.

 

[bustah]

no

its outside the reach of diagnostics! the only way to check it is by swopping over to a new unit. well worth trying, made a big difference on my GS, the mechanic at the dealer did the "test"

 

[Taipan]

Heres the plugs (click for enlargement). Thoughts? Opinions?

 

[finglonga]

Look like it may be running a bit lean to me.

It that from doing a plug chop?

 

[Taipan]

Look like it may be running a bit lean to me.

It that from doing a plug chop?

I'd just belted it down a main A road near me. I decided to check them as part of tracking down whats wrong with the bike.

I have a set of new plugs coming from Steptoe anyway. But these look old to me and also look lean to me?

I've put the Techlusion on tonight and wil try and get it on the dyno in the next few days, but am waiting for a Pipercross airfilter. But from just going round the block it seems much stronger, just about everywhere and its also louder!

 

[Steptoe]

checking the plugs isn't going to tell you if the fuel is getting through, or if it's sparking correctly over 5k revs -

 

[Taipan]

checking the plugs isn't going to tell you if the fuel is getting through, or if it's sparking correctly over 5k revs -

The dyno should confirm the fuelling. Dunno about the spark though?

Suprised BMWs diagnostics thingy cant check the component? There must be a resistance reading to be had from the coil/plug cap unit?

Mind you, in my dim and distant past when I used a Sun tester thingy to check plug leads, you had to wiggle them about to see if the reading launched skywards. Bit difficult with a solid plug cap thing I suppose?

I'll get there, eventually. If not, do you keep pistons in stock?

 

[Taipan]

Bike is getting on my nerves now. Shame cos the techlusion box has really beefed up the bottom end. I still have this power loss/misfire type-o-thing though.

I appreciate its going to need hooking up to BMWs diagnostic thing, but I really don't want to put it into a BMW dealers without trying a few things first. I keep thinking if it was missing, wouldn't the plugs be sooty?

Or maybe I should just replace the integral coil/plug caps anyway. Anyone know how much they are?

If I do bite the bullet and have to stick it into a dealer, are Cannons any good? I certainbly dont want it going back to P**k l**e BMW considering how it came out of there.

I used to use Brackens for my KTM, any one know if they have a BMW diagnostic thing?

Many thanks

 

[Taipan]

Or maybe I should just replace the integral coil/plug caps anyway. Anyone know how much they are?

At the risk of being accused of talking to myself, teh plugcap/coil thingys are £53.51 + VAT. I spoke to avery nice helpful Lady at Cannons BMW. So i think I'll buy one of them and try it on each pot to see if it cures it. She said they rarely need to replace both at once.
So I may just risk the £63 involved then moan like hell if it isnt it

 

[cookie]

try running without the main coil pack leads connected at all. sometimes they will run fine on the secondary if the faulty plug is not trying to spark.

 

[Taipan]

try running without the main coil pack leads connected at all. sometimes they will run fine on the secondary if the faulty plug is not trying to spark.

Hi Mate.

I didnt get to try that as I ordered the plug cap thing and it arrived this morning.

I fitted it and it seems to have pretty much cured everything. My idle has jumped up by about 300rpms. So I assume that was the problem.

I think I'll order the other one as well. if one went I expect the other will follow suit soon? So I'll preempt that situation.

I'll get the bike ona dyno next week hoipefully and get the techlusion dialled in properly and then I should (finally) be a happy bunny

Thanks for all the help and advice everyone. Even though mines a Rockster, I'll still hang around here and pretend its a GS if thats ok? This is a great BMW site with some good knowledge on here.

best,

Dave